AT&T MERLIN LEGEND Release 3.1 System Manager's Manual page 284

Changing Disallowed Lists
Only two- or three-digit star codes are recognized. Two-digit star codes
must begin with 1, 4, 5, 6, 7, 8 or 9. Three-digit star codes must begin
with a 2 or a 3.
The star code or codes must come at the beginning of the string of digits
dialed, not at the end or in the middle. Multiple leading star codes are
allowed for dialing, although not in Allowed/Disallowed Lists. For
example, *67*705551212 is recognized correctly, but in
5551212*67*705553131 the stars are ignored.
To prevent rotary phone users from using all star codes, include a
separate Disallowed List entry, 11 . To disallow specific codes, create
separate entries where 11 is substituted for the *, for example, 1167 .
Beginning with Release 3.1, a default Disallowed List (number 7) is provided
with the system. This Disallowed List is automatically assigned to both generic
and integrated VMI ports used by voice messaging systems. It includes the
following entries, which are often used for toll fraud:
0, to prevent international calls
10, to prevent access to long-distance service providers
1809, to prevent unauthorized international calls routed through the
Dominican Republic
1700, to prevent unauthorized toll calls with a "700" area code
1900, to prevent unauthorized toll calls with a "900" area code
976, to prevent local toll calls to numbers with "976" local access codes
1www976, where "w" stands for a wildcard entry, to prevent long-
distance calls to numbers with "976" local access codes
11, to prevent the use of star codes at rotary telephones
*, to prevent the use of star codes at multiline telephones
Managing the System
6–65